A high-resolution area-change-based capacitive MEMS tilt sensor

Abstract

Tilt sensors have been widely used in many applications, such as instrumentation leveling, oil drilling and structural health monitoring. With the rapid development of the micro-electromechanical system (MEMS) technology, MEMS accelerometer-based high-performance tilt sensors are capable of replacing conventional tilt sensors in most of application fields. High-sensitivity MEMS resonant accelerometers (MRAs) are fully qualified for tilt sensing. However, MRA chips have to be vacuum packaged and require complex circuits; therefore, they are difficult to be miniaturized and commercialized. In this case, this paper introduces a commercial-oriented capacitive MEMS accelerometer for tilt sensing with both high-resolution and compact size. The proposed MEMS sensor utilizes simplified fabrication processes, the area-change-based capacitive displacement transducer and the capacitance-to-voltage conversion application specific integrated circuit (ASIC) for low-cost, high-sensitivity, low power consumption and miniaturization. The developed MEMS sensor has a package dimension of 14 mm × 14 mm × 3.6 mm with a single +5 V power supply and analog voltage output. Several evaluation experiments have been conducted with the results showing that the developed MEMS tilt sensor has a full measurement range of ±180°, a linear measurement range of ±30° with a nonlinearity of ±2.8%, a sensitivity of 33.6 mV/°, a noise floor of 2 × 10−4°/√Hz, a bandwidth of 100 Hz and an angle resolution of 7 × 10−4° with an integral time of 0.5 s. Compared with other commercial MEMS tilt sensors, the proposed sensor has a better resolution, a lower noise floor, a larger bandwidth, a lower power consumption and a smaller package. The simplified fabrication process and high performance suggest the developed MEMS tilt sensor is promising to be competitive in the market.